Background and Aim: Evidence shows that a considerable percentage of Iranian young men suffer from obesity and being overweight at the onset of military services. This study aimed to investigate the soldier's knowledge, attitude and practice about obesity and overweight management based on the Extended Parallel Processes Model.Methods: This KAP (Knowledge, Attitude and Practice) study was conducted in two military centers in Yazd, Iran (in 2016). Through a multi-step sampling method, 94 subjects were recruited. The knowledge, attitude and practice level of soldiers were measured by valid and reliable researcher-made questionnaires. Data were analyzed by descriptive statistics and the Pearson correlation test using SPSS 18.0 software.Results: The mean±SD score was 8.30±1.34 for knowledge, 10.70±1.90 for perceived severity, 9.10±1.69 for susceptibility, 10.11±2.30 for response efficacy, 10.28±2.27 for self-efficacy and 19.70±5.84 for practice of obesity and overweight management. There was a significant direct correlation between the soldiers’ knowledge score and perceived severity (p=0.021). However, knowledge and perceived response efficacy had an inverse and significant correlation (p=0.04). Results also showed a direct significant correlation between perceived self-efficacy and practice (p< 0.001).Conclusion: Soldiers did not have ideal knowledge, attitude, and practice towards obesity management. Therefore, it is suggested to use proper educational intervention for improving these variables in soldiers who are overweight or obese during military service.